self.onmessage = function(e) {
	transAudioData.transcode(e.data)
}
let transAudioData = {
	transcode(audioData) {
		let output = transAudioData.to16kHz(audioData)
		output = transAudioData.to16BitPCM(output)
		output = Array.from(new Uint8Array(output.buffer))
		self.postMessage(output)
		// return output
	},
	to16kHz(audioData) {
		var data = new Float32Array(audioData)
		var fitCount = Math.round(data.length * (16000 / 44100))
		var newData = new Float32Array(fitCount)
		var springFactor = (data.length - 1) / (fitCount - 1)
		newData[0] = data[0]
		for (let i = 1; i < fitCount - 1; i++) {
			var tmp = i * springFactor
			var before = Math.floor(tmp).toFixed()
			var after = Math.ceil(tmp).toFixed()
			var atPoint = tmp - before
			newData[i] = data[before] + (data[after] - data[before]) * atPoint
		}
		newData[fitCount - 1] = data[data.length - 1]
		return newData
	},
	to16BitPCM(input) {
		var dataLength = input.length * (16 / 8)
		var dataBuffer = new ArrayBuffer(dataLength)
		var dataView = new DataView(dataBuffer)
		var offset = 0
		for (var i = 0; i < input.length; i++, offset += 2) {
			var s = Math.max(-1, Math.min(1, input[i]))
			dataView.setInt16(offset, s < 0 ? s * 0x8000 : s * 0x7fff, true)
		}
		return dataView
	},
}